Patent GB-1412136-A (GB)
Title: Telecommunication network
IPC: H04Q11/04
Filed: 1972-10-23
Abstract: 1412136 Automatic exchanger systems PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 23 Oct 1972 [26 Oct 1971] 48710/72 Heading H4K In a hierarchial PCM, t.d.m. exchange system, comprising a plurality of switching modules which are of a lower order in the hierarchy than at least one higher order switching module, groups of incoming and outgoing 128 time slot highways 103, 104; 107, 108 &c. are connected to respective lower order switching modules 100, 101, &c. which switch traffic within their own groups in a known non- blocking time division manner and the lower order switching modules are coupled to a second order switching module 115 where traffic is switched between lower order switching modules over a cross point array 128, the traffic from the lower order switching modules being concentrated on to 16 Î 128 time slot super highways 122-129 prior to the space division switching. The lower order switching modules may be individual spatially opposite exchanges with the higher order switching module forming a tandem exchange. Alternatively all the switching modules may be parts of the same exchange. The incoming and outgoing highways 103, 104; 107, 108 &c. may be connected via concentrators to the subscribers. Details :- Lower order switching module (Fig. 3, not shown).-Provision is made for switching traffic between 32 incoming and 32 outgoing 128 time slot highways with zero blocking and for this purpose a 33 x 180 time slot superhighway (226) is utilized. Each incoming highway is connected via a buffer to a series of 128 storage locations which are coupled via a multiplexer to the superhighway (226). A demultiplexer connects the superhighway to send units of the outgoing highways. By a known operation of the multiplexer/demultiplexer information on any incoming highway channel can be switched to the required outgoing highway channel. Parallel transmission of P.C.M. words may be used through the switching module. Higher order swtiching module. 115 (Fig. 2).- Traffic incoming from each lower order switching module 101-102 is concentrated on to a respective receive superhighway 122-124 via a corresponding multiplexer 116-118. Information is then switched via crosspoint matrix 128 to the same time slot on the required send superhighway 125-127. No provision is made for switching information between the receive and send superhighways associated with the same lower order switching module. No interchange of time slots takes place in the higher order switching module and information received during a time slot x on an incoming highway, e.g. 105 will be transmitted during the same time slot on the required send highway, e.g. 109. The crosspoints are operated in pairs from information contained in cyclic stores 131 -133 thereby enabling a two way connection to be established between the pair of lower order switching modules. In large exchange systems where the lower order switching modules are individual exchanges some provision for direct connections between lower order switching modules may be made. The higher order switching module or tandem exchange the only switches overflow traffic or provides for alternative routing.